Formaldehyde was classified as a Group I Carcinogen by the International Agency for Research on Cancer (IARC) in 2006. While the IARC has stated that there is a lack of evidence that formaldehyde causes brain cancer, three meta-analyses have consistently reported a significantly higher risk of brain cancer in workers exposed to high levels of formaldehyde. Therefore, we report a case of a worker who was diagnosed with glioblastoma after being exposed to high concentrations of formaldehyde while working with formaldehyde resin in the paper industry.

A 40-year-old male patient joined an impregnated paper manufacturer and performed impregnation work using formaldehyde resin for 10 years and 2 months. In 2017, the patient experienced a severe headache and visited the hospital for brain magnetic resonance imaging, which revealed a mass. In the same year, the patient underwent a craniotomy for brain tumor resection and was diagnosed with glioblastoma of the temporal lobe. In 2019, a craniotomy was performed owing to the recurrence of the brain tumor, but he died in 2020. An exposure assessment of the work environment determined that the patient was exposed to formaldehyde above the exposure threshold of 0.3 ppm continuously for more than 10 years and that he had high respiratory and dermal exposure through performing work without wearing a respirator or protective gloves.

This case report represents the first instance where the epidemiological investigation and evaluation committee of the Occupational Safety and Health Research Institute in Korea recognized the scientific evidence of work-related brain tumors due to long-term exposure to high concentrations of formaldehyde during impregnated paperwork. This case highlights the importance of proper workplace management, informing workers that prolonged exposure to formaldehyde in impregnation work can cause brain tumors and minimizing exposure in similar processes.

In 2019, the International Agency for Research on Cancer re-evaluated the carcinogenicity of night-shift work and reported that there is limited evidence that night-shift work is carcinogenic for the development of prostate cancer. Therefore, in 2020 and 2021, the Korean Epidemiologic Investigation Evaluation Committee concluded that 2 cases of prostate cancer were occupational diseases related to the night-shift work. Here, we report the 2 cases of prostate cancer in night-shift workers which were first concluded as occupational diseases by the Korean Epidemiologic Investigation Evaluation Committee.

Patient A: A 61-year-old man worked as a city bus driver for approximately 17 years, from 2002 to 2019, and was exposed to night-shift work during this period. In March 2017, the patient was diagnosed with high-grade prostate cancer through core-needle biopsy after experiencing stinging pain lasting for 2 months. Patient B: A 56-year-old man worked as an electrician and an automated equipment operator in a cement manufacturing plant for 35 years from 1976 to 2013 and was exposed to night-shift work during this period. In 2013, the patient was diagnosed with high-grade prostate cancer through core needle biopsy at a university hospital because of dysuria that lasted for 6 months.

The 2 workers were diagnosed with high-grade prostate cancer after working night shifts for 17 and 35 years respectively. Additionally, previous studies have reported that high-grade prostate cancer has a stronger relationship with night-shift work than low or medium-grade prostate cancer. Therefore, the Korean Epidemiologic Investigation Evaluation Committee concluded that night-shift work in these 2 patients contributed to the development of their prostate cancer.

It is widely known that carbon dioxide (CO₂) arc welding generates carbon monoxide (CO). However, to the best of our knowledge, no case reports have been published regarding CO poisoning in CO₂ arc welders. Therefore, we aimed to report a case of CO poisoning-induced encephalopathy in a CO₂ arc welder in the Republic of Korea to inform about the dangers of CO exposure among CO₂arc welders.

A 40-year-old man working as a CO₂ arc welder for 15 years visited a local hospital with a tremor, involuntary urination, and speaking gibberish, on April 9, 2019. He stated that he had intermittent headache and forgetting symptoms for the last 5 years, and had been lost on the way to work several times. On April 9, 2019, he was diagnosed with CO poisoning-induced encephalopathy through brain magnetic resonance imaging. He received hyperbaric oxygen therapy, and some of his symptoms improved. According to the exposure assessment of his work environment, he was continuously exposed to high concentrations of CO for 15 years while operating CO₂ arc welding machines.

After evaluating the patient's work environment and evaluating his medical history, we concluded that his encephalopathy was caused by CO exposure during CO₂ arc welding. Thus CO₂ arc welders must be aware of the risk of CO poisoning and strive to avoid CO exposure.